Objective. Laminar necrosis, a band-like distribution of coagulative necrosis, has been reported at the choriodecidual interface of the free membranes of placentas of women with various adverse neonatal outcomes. Our goal in this study was to evaluate the frequency of an equivalent feature in the decidua basalis, diffuse decidual leukocytoclastic necrosis (DDLN), a diffuse coagulative necrosis admixed with karyorrhectic debris, in preterm births <32 weeks, and to determine its association with various obstetric conditions, markers of placental inflammation, and newborn outcome. Study design. Four hundred and forty-six mother/infant dyads who delivered between 23 and 32 weeks gestational age (GA) had their medical records abstracted, a variety of placental and cord blood cultures performed, cord interleukin-6 (IL-6) levels determined, and the placentas evaluated histologically by a single pathologist (OFP). Results. Women with DDLN (27%) were significantly more likely than other women to have preeclampsia (57.6 vs. 24.8%, p < 0.0001), an indicated preterm birth in this pregnancy (61.9 vs. 26.4%, p < 0.0001), and a prior indicated preterm birth (12.7 vs. 4.1%, p = 0.001), but were not more likely to have an abruption, diabetes, to smoke or be Black. Among DDLN-positive vs. DDLN-negative women, birth weight was significantly lower (1069 ± 373 vs. 1171 ± 389 g, p = 0.014), despite the GAs being similar (28.6 ± 2.2 vs. 28.6 ± 2.3 weeks, p = NS). Women with DDLN were less likely to have a positive placental culture for any organism (50.0 vs. 61.3%p = 0.03), Ureaplasma urealyticum and Mycoplasma hominis in either the placenta or cord blood (29.7 vs. 42.1%, p = 0.02), or an elevated cord blood IL-6 (21.5 vs. 32.9%, p = 0.059). They also were less likely to have acute inflammation of the membranes (27.4 vs. 56.4%, p < 0.0001), chorionic plate (17.0 vs. 48.6%, p < 0.0001) or cord (15.7 vs. 36.6%, p < 0.0001). Decidual necrosis in the free membranes also occurred more frequently in the presence vs. absence of DDLN (25.2 vs. 9.2%, p < 0.0001). Infants whose placentas had DDLN were significantly less likely to have neonatal systemic inflammatory response syndrome (20.7 vs. 35.2%, p = 0.004), but were not significantly different for other neonatal outcomes including respiratory distress syndrome, intraventricular hemorrhage or death. Conclusion. DDLN of the decidua basalis is relatively common in placentas of 23-32 week newborns, and, when present, is inversely associated with inflammatory maternal and newborn conditions and positively associated with preeclampsia, indicated preterm birth, and lower birth weight. The positive correlation of DDLN with obstetrical and neonatal conditions associated with underperfusion of the placental bed, suggests that DDLN may be a marker of vascular compromise. © 2007 Informa UK Ltd.